The present invention relates to an apparatus for winding a filament onto a former.
In our UK Pat. No. 2,001,400, there is described an apparatus (shown in FIG. A) suitable for the production of brush seals in which an annular mandrel is mounted for rotation in rollers and carries a pair of annular side plates on its side faces adjacent its radially outer periphery. The mandrel is arranged to pass through an annular filament carrier which is channel-shaped and on which is wound a continuous filament of metallic bristle material. The filament carrier is supported for rotation in a plurality of rollers, one of which is connected to a drive shaft for rotating the carrier, and a similar driving arrangement is used for driving the rollers which support the mandrel. Rotation of the mandrel and the filament carrier causes bristle material to be continuously supplied from the filament carrier, via a slider which tensions the filaments, and wound onto the mandrel to overlie the outer side surfaces of the side plates.
This apparatus, whilst producing adequate seals, suffers from a number of disadvantages due to its design. Several filaments of brush material are bunched together on the carrier, resulting in uneven tension, overlaps, and wire breakages. The slider tends to stick and slip during operation which causes uneven tension and breakages. The erratic movement of the slider also results in a lack of angle control. The filaments are passed through tight radii during winding which makes subsequent heat treatment essential to remove any tendency for the filaments to curl up in the finished brush.
The above mentioned patent also describes an alternative winding mechanism which uses multiple filaments for speeding up the winding process (shown in FIG. B). In this embodiment, eight spools of filament material are mounted upon the carrier and each spool feeds a filament of brush material onto the mandrel. The filaments from the spools are passed through holes in one side of the side plates of the spool carrier to ensure that they always emerge in the same plane to avoid variation in the winding angle as the spools unwind.
The spool carrier is hinged at one position and provided with a latch to enable the annular mandrel to pass through the inside thereof.
The alternative winding mechanism overcomes a number of the problems associated with the first described apparatus. However, some problems remain and others are introduced. The filaments are still passed through tight radii which results in subsequent heat treatment being required and/or wire breakages occurring. Further to this, the carrier is considerably more complex and difficult to load with bobbins of filament material.